Device for maintaining a photographic processing solution at a predetermined composition



Feb. 13, 1968 L. P. VAN BOUWEL ET AL 3,368,472

DEVICE FOR MAINTAINING A PHOTOTOGRAPHIC PROCESSING SOLUTION AT APREDETERMINED COMPOSITION Filed Dec. 21, 1964 I r I 1 I I I I awdz, mwwwATTORNEYS INVENTORS' 3,368,472 DEVICE FOR MAINTAINING A PHOTOGRAPH- ICPROCESSING SOLUTION AT A PREDETER MINED COMPOSETION Leo Paul Van Bouwel,Mortsel-Antwerp, and Willy Pieter Tack, Berchem-Antwerp, Belgium,assignors to Gevaert Photo-Producten N.V., Mortsel, Belgium, a Belgiancompany Filed Dec. 21, 1964, Ser. No. 419,727 Claims priority,application Netherlands, Dec. 20, 1963,

302,435 Claims. (Cl. 95-89) ABSTRACT 0F Til-IE DISCLOSURE When asufficient amount of photographic material has been processed to requirereplenishment of the processing solution, a measuring device actuates aflow of fresh solution to a measuring tank. When the desired level ofsolution is reached in the tank, a float stops the flow of solutiontherein and a self-starting siphon discharges the contents of the tankuntil the siphon is broken by the lower level of solution. The effectivevolume of the tank and the intake end of the siphon can be adjusted.

The invention relates to a device for maintaining a photographicprocessing solution at a predetermined composrtion.

ln the processing of light-sensitive and photographic material it isdesirable for the developing solution to be of substantially constantcomposition otherwise the time and temperature for obtaining a standarddegree of development will vary. Thus in developing large quantities oflight-sensitive material on a continuous process basis, it is necessaryto replenish the developer solution at substantially the same rate as isbeing consumed.

The volume of a replenishing liquid can be determined either bycalculation or by experiment to restore a photographic processingsolution to its former composition after processing a known amount oflight-sensitive material under known conditions.

It is known to practice devices for maintaining a photographicprocessing solution at a predetermined composition wherein at a certainmoment a constant amount of replenishing liquid or solution is added toa photographic processing bath. Such devices usually comprise a smallmeasuring container which is provided with a feed valve and a dischargevalve and which is. arranged to contain a constant amount of solution.

Each time the discharge valve is opened, a constant amount of processingsolution is flowed from the container to the photographic processingbath situated therebeneath. After the container has been emptied, thedischarge valve is closed, the feed valve is opened and by gravity or bymeans of a pump the container is refilled with replenishing solutionfrom the storage tank.

Practice has proved that an accurate volumetric dosing cannot beobtained by means of a device of the kind mentioned above.

Due to crystallization of the replenishing solution at the valves of thecontainer these valves can no longer fully be closed. In case the valvesare formed by flexible tubes which are pinched, the rapid ageing of theflexible material of the tubes causes troubles.

The object of the present invention is to provide a device formaintaining a photographic processing solution at a predeterminedcomposition, which does not show the mentioned disadvantages and whichpermits to add a constant amount of replenishing solution to aphotographic processing bath.

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a device for maintaining a photographic solution at a predeterminedcomposition, wherein the amount of re- Another object of the presentinvention is to provide I plenishing solution which has to be added isadjustable in a very accurate way.

A further object of the invention is to provide a device which is verysimple of construction and which requires but little periodicalmaintenance.

The device for maintaining a photographic solution at a predeterminedcomposition according to the present invention, comprises a measuringcontainer for holding a given quantity of replenishing solution, meansfor feeding replenishing solution from a storage tank to said container,a siphon in said container with the shorter leg extending in the lowerportion of the container, thereby determining the lower level of thereplenishing solution in the container, the longer leg of the siphonextending under the bottom of said container and conducting to the lowerlocated photographic processing solution, and the intermediate elevationbetween both legs being located at the high level the replenishingsolution attains in said container, the attainment of the said highlevel of the replenishing solution in the container being measured by afloat which controls the means for feeding the replenishing solutionfrom the storage tank to the container so as to arrest the feed of thereplenishing solution once the level of the solution has attained thesaid intermediate elevation of the siphon, and means for measuring theamount of photographic material which has been treated in thephotographic processing solution and for controlling the starting of themeans for feeding the replenishing solution to the container after agiven amount of photographic material has been processed.

The term amount of photographic material as used hereinbefore denotestheoretically a determined area of such material but, since in practice.the length of the processed photographic material is often measuredinstead of the area thereof, we wish to extend the scope of the saidterm in the present invention also to the latter significance.

The feeding of the replenishing solution from the storage tank to themeasuring container may occur either by gravity or by a pump.Alternatively, an over-pressure may be maintained in the storage tank,e.g. by means of a nitrogen atmosphere.

According to a particular embodiment of the present invention the siphonis in the form of a U bent tube with legs of uneven length. Said siphonis positioned vertically in the container so that the opening of theshort leg is situated near the bottom of the container and the long legpasses through the bottom to extend outwardly.

With reference to the accompanying drawing the invention is illustratedby the following embodiment.

FIG. 1 represents a diagrammatic view of the measuring containers andthe storage tanks of a device according to the present invention.

FIG. 2 represents the electric circuit controlling the device of FIG. 1.

FIGURE 3 is a fragmentary view of the short end of siphon of thearrangement in FIGURE 1, showing an adjustable collar to permitadjustment in the lower level of solution in the measuring container.

FIGS. 1 and 2 show a device for maintaining a photographic processingsolution at a predetermined composition.

This device comprises the housing 11 which is divided into two measuringcontainers 13 and -14 by the partition 12. The container 13 is filledwith the replenishing solution for the developing bath and the container14 is filled with the replenishing solution for the fixing bath of aphotographic processing apparatus.

Each of the containers is provided with a float 15 Which is verticallymovable in a guider 16, a plunger 17 consisting of a cube with inwardscrew thread, this cube being fitted to a rotatably journalled screwbolt 18, and a siphon 19 having a short leg 20 and a longer leg 21. Ahose is connected to the leg 21, conducting to the lower locateddeveloping bath resp. fixing bath of the processing apparatus.

The high level of the solution in the containers is indicated by thebroken line 22, the low level is indicated by the broken line 23.

In its highest position the float in the container 13 artuates themicroswitch S the float in the container 14 actuates the microswitch SThe housing 11 and the partition 12, together with the floats 15, theguiders 16, the plunger 17 and the siphons 19, are made out of hardpolyvinyl chloride. One of the side walls of the housing 11 is made outof synthetic glass so that the level of the solution in the containerscan be easily watched.

The pump 24 pumps the replenishing solution for the developing bath froma storage tank 25 to the container 13 by means of the feed line 26.Similarly replenishing solution for the fixing bath is pumped by thepump 27 from the storage tank 28 to the container 14.

The operation of the replenishing system for one container (13) is nowdescribed in a summarizing way. Thereafter a detailed description of thecomplete device and of the electric control system is given.

At the moment of replenishing the pump 24 driven by the electric motor Mis actuated. Solution is pumped from the tank 25 to the container '13until the solution in the container has reached the level indicated bythe broken line 22. At that moment the float actuates the microswitch Sso that the motor M is switched ofi and the filling of the containerceases. At the same moment the level of the solution has also reachedthe intermediate elevation of the siphon, so that the solution starts toflow through the siphon until reaching the low level indicated by thebroken line 23. At this moment the contact between the level of thesolution and the opening of the short leg of the siphon is interruptedso that the solution ceases flowing away.

It is clear that the level of the solution rises and lowers at eachreplenishing cycle over a constant distance, i.e. the difference inheight between the levels indicated by the broken lines 22 and 23.Thereby the volume of replenishing solution, which is added during eachcycle to the photographic bath, is accurately constant.

The volume of replenishing solution can be reduced by providing anelement such as the plunger 17 in the container. Moreover by making thisplunger adjustable in the height, the volume of solution added to thebath at each cycle can be accurately controlled. In the presentembodiment the plunger 17 can be adjusted by means of the screw bolt 18.The plunger 17 which has a square diameter will slide with one of itsflat sides along the side wall of the container 13 upon turning thescrew bolt 18. Consequently the plunger will not turn together with thescrew bolt and a turning movement of the latter makes the plunger riseor lower.

The operation of the complete device and of the electric control systemis as follows.

The contact s of a microswitch, which is provided at the entrance, ofthe processing apparatus and which is closed by a film sheet movingalong, closes the circuit of the motor M This motor is provided with areduction gear and drives the cam disk 30. When the film sheet haspassed the microswitch in the proceessing apparatus, the contact s isre-opened and the motor M is stopped. This opeeration is repeated foreach film sheet. It is clear that the cam disk acts here as anintegrator since its angular displacement is proportional to the totallength of the processed film sheets.

When the cam disk 30 has performed one complete revolution its camcloses the contacts .9 and s The contact s closes the circuits of therelays L and L through the diodes D and D The closed contact s providesfor the continuance of the rotation of the cam disk until the cam haspassed beyond the contacts s and s Thereby both contacts are opened andthe motor M stops.

By means of the contact s it is prevented that the cam disk 30 remainsin the position in which the contact .9 has been closed. In such a casethe relays L and L would no longer be capable to drop and, even withouta film sheet causing the contact s to close, the replenishing wouldrepeat continuously.

The relays L and L remain energized over their respective hold-contacts1 and 1 Their contacts 1 and 1 close the circuits of the pump motors Mand M and the containers 13 and 14 become filled with replenishingsolution. At the moment that the surface of the solution has reached thehigh level indicated by the broken line 22, the contacts s and s of therespective microswitches S and S are opened by the floats 15.

It has to be noticed that although the filling of both containers isstarted at the same moment, the filling operation of one container canbe ceased prior to ceasing the filling of the other container. Therebyit becomes possible to make both containers feed solution volumes whichare different from each other. Moreover, then the dosing device iscompletely independent from differences in the output of both pumps,from occasional foam-forming in the pipe lines from the pumps to thecontainers, etc.

When opening the contacts s s the relays L L are dropped. In case thatone of the contacts opens before the other, the diodes D and D providefor the dropping of both relays independently from each other.

The electric diagram of the device according to the present inventionalso shows a contact s This contact, Which belongs to a secondmicroswitch situated near the first mentioned microswitch but laterallyspaced therefrom at the entrance of the photographic processingapparatus, has the following function.

As already mentioned hereinbefore the quantity of solution to bereplenished is theoretically direct proportional to the surface of theprocessed film sheets. The microswitch With the contact s only measuresthe length of the processed film sheets and thus the integration whichis made by the cam disk 30 is only correct for one defined film size.Since in practice film sheets of different sizes are processedarbitrarily among each other, an exact dosing of the replenishingsolution is impossible. By taking an average value for the difierentsizes of film sheets, the theoretical dosing can be approximately verywell in practice.

This close approximation is still enhanced by dividing the differentsizes of film sheets into two groups, viz. a group comprising smallersizes and a group comprising greater sizes of film sheets.

All the film sheets of both groups will close the contact s Only thefilm sheets belonging to the group of the greater sizes will close alsothe contact s The resistor R is short-circuited by s so that the motor Mwill rotate at a higher speed and correspondingly the replenishingaction will take place sooner.

By providing some more laterally spaced microswitches at the entrance ofthe photographic processing apparatus having each their influence on thespeed of the motor M the accuracy of the dosing device is still furtherincreased.

The resistors R and R can also be arranged in an adjustable way. Therebycorresponding resistance values may be set for a determined bathcomposition, bath temperature, processing speed, etc. said valuesassuring optimal results of the replenishing.

It is clear that the electric system controlling the replenishing systemmust always meet the requirement that its period will be greater thanthe time for filling and emptying of the containers.

Indeed, if the cam disk 30 would be capable of performing one revolutionduring a time which is smaller than the time for filling and emptying acontainer, then the filling of the container during a following cyclecould be started before the level of the solution in the container wouldbe lowered again until reaching the level 23. An accurate dosing wouldthen be excluded.

In the given example of embodiment the adjustment of the volume of thereplenishing solution is done by means of the plungers 17. It is clearthat also other means can be applied for determining said solutionvolume. For example as shown in FIGURE 3, the short leg 20' of thesiphon can be provided with a collar 20a arranged in a telescopingrelationship with its lower end and having a sliding friction fittherewith. Thus, the position of the eifective in take opening of theshort siphon leg can be adjusted with respect to the container bottom.For example; by sliding the collar more downwardly the lower solutionlevel indicated by the broken line 23 will decrease so that thereplenishing volume increases.

It is not necessary to arrange the siphon in the container but it mayalso be positioned near the container, the extremity of the short legcommunicating with the container.

The device according to the present invention can also be used in thephotographic industry for replenishing stop baths, bleaching (fixing)baths, tanning bath, etc.

We claim:

1. Device for maintaining a photographic processing solution at apredetermined composition, comprising a measuring container for holdinga given quantity of replenishing solution, means operable to feedreplenishing solution from a supply tank to said container, means formeasuring the quantity of material being processed, means responsive tosaid measuring means when a predetermined quantity of material has beenprocessed for operating said solution feeding means, means for haltingsaid feeding means, when the solution level in said container attain apredetermined maximum, anda siphon having a short leg extending withinsaid container with its lower end opening spaced from the containerbottom to thereby determine a minimum level of solution in saidcontainer, a long leg for discharging the solution outside and below thecontainer into the processing solution, and a bight connecting the upperends of said legs, said bight being disposed at said maximum level,whereby said solution discharges through said siphon after reaching saidmaximum level and continues to discharge until said lower level isreached.

2. Device according to claim 1, wherein means is provided for varyingthe effective volumes of said container below the high level.

3. Device according to claim 2, wherein said means comprises adisplaceable plunger.

4. Device according to claim 3, wherein the said plunger is arranged forvertical displacement by means of a vertical rota-tably journalledthreaded rod.

5. Device according to claim 1, wherein the extremity of the shorter legof the siphon is provided with a vertically adjustable collar.

References Cited UNITED STATES PATENTS 440,325 11/ 1890 Richards 95892,229,122 1/ 1941 Pershing 137-132 2,778,734 1/ 1957 Fairbank. 2,837,9886/1958 Pavelle 9589 3,062,123 11/1962 Limberger 95-89 NORTON ANSHER,Primary Examiner.

FRED BRAUN, Assistant Examiner.

